Just to comment on this thread, I think some people are trying to read a bit too much into certain things.

The example that MikeT posted shows pretty clearly the relationship between +/- and pitching, and it's not that difficult to quantify.

Adjusting for IP, Mike's pitchers allowed about 61 fewer non-HR hits in S10 than they did in S9. Their +/- was 53 better. Pretty simple. Generally speaking, for every 1 increase in +/-, you save about 1 hit. You can ballpark the value of a hit at about a half of a run. So, every 1 increase in +/- saves you about half a run. Not too complicated.

Posted by jtrinsey on 2/15/2013 5:16:00 PM (view original):Just to comment on this thread, I think some people are trying to read a bit too much into certain things.

The example that MikeT posted shows pretty clearly the relationship between +/- and pitching, and it's not that difficult to quantify.

Adjusting for IP, Mike's pitchers allowed about 61 fewer non-HR hits in S10 than they did in S9. Their +/- was 53 better. Pretty simple. Generally speaking, for every 1 increase in +/-, you save about 1 hit. You can ballpark the value of a hit at about a half of a run. So, every 1 increase in +/- saves you about half a run. Not too complicated.

Not all + plays are "hits turning into outs". That's overly simplistic, and generally inaccurate.

I had a SS type with 90+ arm ratings who I played in CF for a number of seasons. He had a ton of + plays every season. But when I went through play by play one season to get a better understanding of exactly what he was doing for me defensively, I saw that most of his + plays were on base hits. I think his arm was deterring singles from being stretched into doubles (as they may have been on a more "average" CF). Still a valuable thing, but certainly not the same value as turning hits into outs.

Not to be argumentative, which means I'm going to be argumentative, but, if you're going to develop a formula, you have to create a value for a play. Errors are what they are. A plus play could be turning a hit into an out or preventing an extra base. A negative play could be turning an out into a hit(range) or allowing an extra base. In all cases, the play prevented/allowed a runner to move to another station.

So, unless you're going to look at box scores to determine the "true" value of a +/- play, you have to treat them as allowing/preventing the movement from station to station.